In a study of 411,737 cell phone users, it was found that 65 developed cancer of
ID: 3056087 • Letter: I
Question
In a study of 411,737 cell phone users, it was found that 65 developed cancer of the brain or nervous system. Assuming that cell phones have no effect, there is a 0.000171 probability of a person developing cancer of the brain or nervous system. We, therefore, expect about 71 cases of such cancer in a group of 411,737 people. Estimate the probability of 65 or fewer cases of such cancer in a group of 411,737 people. What do these results suggest about media reports that cell phones cause cancer of the brain or nervous system?
(a) P(65 )=
(b) What does the result from part (a) suggest about the media reports?
Explanation / Answer
Pr(Person developing cancer of he brain or nervous system) = 0.000171
Here standard deviation of number of people who developed cance sd(p) = sqrt [p * (1-p) *N] = sqrt [0.000171 * (1 - 0.000171) * 411737]= 8.39
(a) P(x 65 ) = Pr(x65 ; 71; 8.39)
by doing continutiy correction
Pr(x65 ; 71; 8.39) = Pr(x < 65.5 ; 71; 8.39)
Z= (65.5 - 71)/8.39 = -0.655
P(x 65 ) = Pr(x < 65.5 ; 71; 8.39) = Pr(Z < -0.655) = 0.2562
(b) Here as p - value is not less 0.05 so we cannot reject the null hypothesis so we can disccard the results of media reports that cell phone cause cancer of the brain or nervous sysstme.